Semiconductor wafers, flat panel displays and other similar substrates typically have numerous material layers deposited thereon during device fabrication. Some commonly deposited layers (e.g., spin-on glass (SOG) films) may contain contaminants, defects of undesirable microstructures that can be reduced in number or altogether removed by heating or “annealing” the substrate at an appropriate temperature for an appropriate time. Other deposited layers (e.g., copper films) may have properties that undesirably change over time or “self-anneal”, resulting in unpredictable deposited layer properties (e.g., unpredictable resistivity, stress, grain size, hardness, etc.). As with contaminants, defects and undesirable microstructures, deposited layer properties often can be stabilized by a controlled annealing step (e.g., for copper films, a 200-400° C., 15 second 3 minute anneal in a gas such as N2 or about 96% N2, 4% H2). Following any annealing step, a substrate preferably is rapidly cooled so that other processes can be performed on the substrate without delay (i.e., to increase throughput).
Conventionally annealing is performed within a quartz furnace that must be slowly pre-heated to a desired annealing temperature, or within a rapid thermal process (RTP) system that can be rapidly heated to a desired annealing temperature. Thereafter an annealed substrate is transferred to a separate cooling module which conventionally employs a cooled substrate support and is slightly backfilled with a gas such as argon to enhance thermal conduction. The separate cooling module increases equipment cost and complexity, as well as equipment footprint, and decreases substrate throughput by requiring substrate transfer time between the heating and cooling systems. Accordingly, a need exists for an improved method and apparatus for heating and cooling substrates that is less expensive, less complex, and has a reduced equipment footprint and increased throughput when compared to conventional substrate heating and cooling systems.